Device for producing cold at low temperatures and compression devices suitable for use in said devices



y 1957 J. R. VAN GEUNS 3,318,101

DEVICE FOR PRODUCING COLD AT LOW TEMPERATURES AND COMPRESSION DEVICES SUITABLE FOR USE IN SAID DEVICES Filed Feb. 4, 1965 3 Sheets-Sheet 1 FIG] INVENTOR. JOHANNES R .VAN GEUNS v AGEN. I

May 9, 1967 J. R. VAN GEUNS 3,318,101

DEVICE FOR PRODUCING com) AT LOW TEMPERATURES AND COMPRESSION DEVICES SUITABLE FOR usE IN SAID DEVICES Filed Feb. '4, 1965 3 Sheets-Sheet 2 INVENTOR JOHANNES R.VAN GEUNS y 1967 J. R. VAN GEUNS 3,318,101

DEVICE FOR PRODUCING COLD AT LOW TEMPERATURES AND COMPRESSION DEVICES SUITABLE FOR USE IN SAID DEVICES Filed *Feb. 4, 1965 3 Sheets-Sheet 5 FIG.5

INVENTOR. J0 HANNES R.VAN GEUNS 249.41 Aug AGENT United States Patent 3,318,101 DEVICE FOR PRODUCING COLD AT LOW TEM- PERATURES A N D COMPRESSION DEVICES SUITABLE FGR USE IN SAID DEVICES Johannes Rudolphus van Geuns, Emmasingel, Eindhoven,

Netherlands, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Feb. 4, 1965, Ser. No. 430,402 Claims priority, application Netherlands, Feb. 4, 1964, 6,401,303 11 Claims. (Cl. 62-6) The invention relates to a device for producing cold at low temperatures, comprising at least one compressor for compressing a working medium, provided with a cooler for conducting the compression heat away, in which an outlet -for compressed medium communicates with a first heat exchanger in which the compressed medium is in thermal contact with expanded medium so that it is cooled. The device furthermore includes a source of cold in which the medium is further cooled, the medium passing, after said source of cold, through a second heat exchanger in thermal contact with expanded medium while the outlet of said second heat exchanger communicates with an expansion member in which the medium expands while the expanded medium flows back at least partly to the compressor.

In devices of the kind according to the invention the use of expensive heat exchangers, usually constructed in the form of recuperators, required in said devices is a great disadvantage. Particularly, if these heat exchangers are balanced, either their efiiciency is very low or their dimensions are very large.

The disadvantages referred to above in connection with the heat exchangers might be overcome by using commutatable regenerators. In the devices of the kind to which the invention relates the pressures involved are, however, so high that the communication of the regenerators is attended with inadmissibly high commutation losses.

The device according to the invention has for its object to overcome said disadvantages and is characterized in that the first heat exchanger is constructed at least partly as a regenerator, the regenerator portion being in open communication with the compression space of the compressor, the outlet valves and the inlet valves being disposed on the side of the regenerator remote from the compression space.

The device according to the invention has the advantage that the heat exchange is performed with a higher degree of efliciency, while commutation of the regenerator is not necessary.

A further advantage is that the regenerator is automatically balanced. 7

An advantage of the device according to the invention resides in that in the part of the device lying after the regenerator the medium is always very clean, since all impurities are frozen out in the regenerator. This means that the working medium of the device need not be very pure, since the impurities are withheld in the regenerator so that the second heat exchanger and the expansion member will not be clogged.

All these advantages render the device according to the invention particularly suitable for producing cold at very low temperatures in a very effective manner.

A further advantageous embodiment of the device according to the invention is characterized, in that both the cooler for conducting away the compression heat and the regenerator are housed in the compression space of the compressor, so that the whole quantity of medium passing through the outlet or the inlet flows through the regenerator and the cooler.

When part of the cold medium, after the expansion member, is conducted away from the device, for example in the form of 1a condensate, the medium must be replenished. According to the invention the compressor is provided with a further inlet along which medium can reach the compression space without passing through the regenerator.

In a further advantageous embodiment of the device according to the invention the source of cold is formed by one or more cold-gas refrigerators, which only cool the medium.

According to a further aspect at least the compression piston of each cold-gas refrigerator is double-acting and the side of this piston remote from the working space varies the volume of a compression space, a regenerator being in open communication with said compression space.

In this manner a particularly simple and compact structure of the device for producing cold at very low temperatures is obtained.

In a further embodiment of the invention the device comprises a plurality of series-connected compressors, while the compression space of each compressor is in open communication with a regenerator associated with the relevant space.

Instead of being connected in series, the compressors may be connected in parallel, in which case the compression space of each compressor is in open communication with an associated regenerator, and the outlet of each compressor communicates with a common bulfer space.

- In a further advantageous embodiment of the invention the working medium is formed by a medium of very low boiling point, for example H or He.

The invention furthermore relates to a compression device particlarly suitable for use in a device according to the invention. This compression device comprises at least one cylinder having a piston-like body movable therein for varying the volume of a compression space, which is provided with one or more inlet valves for expanded medium and outlet valves for compressed medium, there being furthermore provided a cooler for conducting away the compression heat. In accordance with the invention each compression space is in open communication with a regenerator, while the outlet valves and the inlet valves are located on the side of the regenerator remote from the compression space.

According to a further aspect of the invention each of the compression spaces comprises a regenerator and a cooler, which are disposed so that the medium leaving the compression space through the outlet valves or enters it through the inlet valves passes through said regenerator and cooler.

In a further embodiment of the compression device according to the invention each compression space is provided with one or more further inlet valves which are arranged so that medium can pass through the compression space without passing through the regenerator. These valves may also serve for replenishing medium in the device.

The invention will be described more fully with reference to the drawing, which shows diagrammatically and not to scale a device for producing cold at low temperatures.

FIG. 1 and FIG. 2 show diagrammatically and not to scale two devices for producing cold at low temperature, each comprising a compressor, a refrigerator and a choke member. The device of FIG. 1 has a closed cycle, so that the medium circulates, whereas the device of FIG. 2 permits of draining condensate, so that the compressor is provided with a supplemental inlet valve for replenishing the medium conducted away in the form of a condensate.

FIG. 3 also shows diagrammatically, not to scale, a device for producing cold at low temperature in which the compression piston of the refrigerator is a doubleacting piston.

FIGS. 4 and show diagrammatically, not to scale, two devices for producing cold at low temperature, in which the device of FIG. 4 comprises two series-connected compressors, whereas the device of FIG. 5 comprises two parallel-connected compressors.

Referring to FIG. 1 reference numeral 1 designates a cylinder in which a piston 2 is adapted to reciprocate. The piston 2 is linked by a piston rod 3 to a driving gear (not shown). The cylinder 1 is extended at the top in a further cylindrical portion 4 of smaller diameter. In this cylindrical portion a pipe cooler 5 and a regenerator 6 are arranged. The cylindrical portion 4- has a diameter which is slightly smaller than the cylinder 1 in order to restrict clearance space. If the choice of the stroke of the piston 2 is free, the diameters of the cylinder 1 and of the cylindrical portion 4 may be equal to each other. The head face of the cylinder 4 is provided with an outlet valve 7 and an inlet valve 8., From the outlet valve 7 a conduit 9 passes to a cooling space around the cold head of a cold-gas refrigerator 11. From this cooling space a duct 12 passes to a heat exchanger 13, with which communicates a duct 14 including an expansion cock 15. The expanded, condensed medium is collected in a vessel 16, in which a spiral 17 is arranged, through which the medium to be cooled is passed. The medium volatilized by the absorption of heat flows through a duct 18, the heat exchanger 13 and the duct 19 back to the inlet valve 8 of the compressor.

The device operates as follows. When the piston 2 moves upwards, the medium in the compression space is compressed, and the compressed medium passes through the cooler *5, where it gives off the compression heat, and the regenerator, Where it is cooled and where any impurities are frozen out, through the outlet valve 7 in the duct 9. The compressed medium is then cooled in the cooling space by the cold head of the cold-gas refrigerator 11. The strongly cooled medium is further cooled in the heat exchanger 13 on expanded medium. Then the very cold medium is passed through the choke cock 15, where it condenses partly. Instead of a choke cock use may be made, for example of an expansion machine, in which the medium expands while furnishing external energy.

The expanded medium is brought in the vessel 16 into thermal contact with the cooling spiral 17. The cooling spiral 17 is traversed by the medium to be cooled. The vo-latilised medium is then passed through the heat exchanger 13, where it cools the compressed medium, back to the inlet valve 8. It will be obvious that the ducts must have an adequate volume for a continuous operation of the expansion cock. If necessary, buffer vessels may be included in the ducts. The returning medium flows again through the regenerator 6, where it gives off its cold and carries along any impurities. In the compression space which operates substantially at room temperature, the medium need therefore not be particularly pure. The medium may be for example hydrogen or helium.

In this manner a device is obtained by which, owing to the regenerator, cold can be produced at low temperature with satisfactory efficiency.

In the device shown in FIG. 2, the construction and the operation of which substantial-1y correspond with those of the device of FIG. 1, the vessel 16 for collecting the condensate is provided with a tap 20. Through said cock at least part of the condensate can be derived as a product. This reduces of course, the quantity of medium in the device. In order to replenish the medium, the compressor cylinder 1 is provided with a further inlet valve 21, which communicates through a duct 22 with a supply vessel for medium (not shown). When a deficient quantity of medium enters through the inlet valve 8 at the suction stroke, the inlet valve 21 will also be opened, so that medium can flow out of the vessel into the device. If this supplementary medium contains impurities, which are frozen out in the regenerator, the regenerator must be cleaned after a given period of time. This can be performed by heating.

FIG. 3 shows a structurally different device for producing cold at low temperatures. This device comprises a cold-gas refrigerator. This refrigerator comprises a displacer piston 31 and a compression piston 32, which are adapted to move in cylinders 33 and 34 respectively with a given phase shift. The displacer piston and the piston can be driven in known manner (not shown). The refrigerator comprises furthermore a cooler 35, a regenerator 36 and a freezer 37, through which elements the medium passes on its way from the compression space 38 to the expansion space 39 or conversely.

The compression piston 32 of this device is a doubleacting piston. The upper side thereof varies the volume of the compression space 38 of the refrigerator and the other side varies the volume of a further compression space 40.

This further compression space 40 communicates through a duct 41 openly with a cooler 42 and a regenerator 43. On the side of the regenerator remote from the compression space there are provided the inlet valve 44 and the outlet valve 45. The medium compressed in the compression space 40 passes through the regenerator 43 and thereafter through a duct 46, along the head of the cold-gas refrigerator and then through the heat ex changer 13 to the choke cock 15. The operation of this device corresponds otherwise with that of the devices shown in FIGS. 1 and 2. The construction of the device shown in FIG. 3 is particularly efficient and compact.

FIG. 4 shows a device for producing cold at low tem* peratures in which the compression member is formed by a two-stage compression device. The operation corresponds with that of the devices shown in the preceding figures.

Finally FIG. 5 shows diagrammatically, not to scale, a device for producing cold at low temperatures, in which two compressors are connected parallel with each other. The outlets of the compressors communicate with a buffer space 50' and the inlets communicate with a buffer space 60. The operation of this device corresponds otherwise with that of the devices shown in the preceding figures.

Although, as is shown in FIGS. 4 and 5, only two compressors are linked in series and in parallel respectively, it will be obvious that the number of compressors may be extended at will.

The devices constructed according to the invention produce cold at low temperatures with a surprisingly high degree of efficiency. The medium present in the device may be hydrogen or helium. As an alternative, a different, suitable medium may be employed in these devices.

I claim:

1. A low temperature device provided with a working medium comprising at least one compressor for compressing said working medium, said compressor being provided with a cooler being in open communication with said compressor, said cooler being adapted to conduct away the compression heat, a first heat exchanger, an outlet valve for said compressed medium being in communication with said first heat exchanger, a cold source traversed by said compressed medium whereby it is further cooled, a second heat exchanger, an outlet for said second heat exchanger, an expansion member in which said medium expands, said outlet for said second heat exchanger communicating with said expansion member, an inlet valve communicating with said first heat exchanger, said expanded medium being passed back at least partly to said compressor through said first and second heat exchangers and said inlet valve whereby said expanded and compressed medium are in thermal contact, said first heat exchanger being at least in part a regenerator, said regenerator part being in open communication with the compression space of said compressor, said outlet and inlet valves being in communication with said first heat exchanger being located at the side of said regenerator remote from said compression space.

2. A low temperature device provided with a working medium as claimed in claim 1 wherein both said cooler and regenerator are housed in the compression space of said compressor whereby the medium passing through said outlet and inlet valves respectively flows through said regenerator and cooler.

3. A low temperature device provided with a working medium as claimed in claim 1 further comprising means for tapping off the medium in the outlet of said expansion member, and another inlet for medium to replenish the medium Withdrawn in said tapping 0E means.

4. A low temperature device provided with a working medium as claimed in claim 1 wherein said cold source is at least one coldgas refrigerator which only cools the compressed medium.

5. A low temperature device provided with a Working medium as claimed in claim 1 wherein the compression piston is a double-acting piston, an additional compression space, and the side of said piston remote from said working space varying the volume of said additional compression space, and an additional regenerator in open connection therewith.

6. A low temperature device provided with a working medium as claimed in claim 1 further comprising a plurality of series-connected compressors, and the compression space of each compressor being in open communication with a regenerator of the associated compressor.

7. A low temperature device provided with a working medium as claimed in claim 1 further comprising a plur-ality of parallel-connected compressors, the compression 6 space of each compressor being in open communication With an associated regenerator, and a common buffer space communicating with both the outlet and inlet valves of each compressor.

8. A low temperature device provided with a working medium as claimed in claim 1 wherein the working medium is a medium of a very low boiling point.

9. A low temperature device provided with a working medium as claimed in claim 1 wherein said compressor includes at least one cylinder, a piston adapted to reciprocate in said cylinder for varying the volume of said compression space.

10. A low temperature device provided with a working medium as claimed in claim 1 wherein each compression space comprises a regenerator and a cooler which are so arranged that the medium Which leaves said compression space through said outlet valve and enters through said inlet valve passes through said regenerator and said cooler.

11. A low temperature device provided with a working medium as claimed in claim 1 wherein each compression space is provided with at least one additional inlet valve which is arranged so that the medium passes therethrough to said compression space without passing through said regenerator.

References Cited by the Examiner UNITED STATES PATENTS 2,764,877 10/ 1956 K-ohler 626 3,078,683 2/1963 Dros 6'2-6 3,101,596 8/1963 Rinia 626 3,115,016 12/1963 Hogan 626 3,148,512 9/1964 Hoffman 6 2-6 WILLIAM J. WYE, Primary Examiner. 

1. A LOW TEMPERATURE DEVICE PROVIDED WITH A WORKING MEDIUM COMPRISING AT LEAST ONE COMPRESSOR FOR COMPRESSING SAID WORKING MEDIUM, SAID COMPRESSOR BEING PROVIDED WITH A COOLER BEING IN OPEN COMMUNICATION WITH SAID COMPRESSOR, SAID COOLER BEING ADAPTED TO CONDUCT AWAY THE COMPRESSION HEAT, A FIRST HEAT EXCHANGER, AN OUTLET VALVE FOR SAID COMPRESSED MEDIUM BEING IN COMMUNICATION WITH SAID FIRST HEAT EXCHANGER, A COLD SOURCE TRAVERSED BY SAID COMPRESSED MEDIUM WHEREBY IT IS FURTHER COOLED, A SECOND HEAT EXCHANGER, AN OUTLET FOR SAID SECOND HEAT EXCHANGER, AN EXPANSION MEMBER IN WHICH SAID MEDIUM EXPANDS, SAID OUTLET FOR SAID SECOND HEAT EXCHANGER COMMUNICATING WITH SAID EXPANSION MEMBER, AN INLET VALVE COMMUNICATING WITH SAID FIRST HEAT EXCHANGER, SAID EXPANDED MEDIUM BEING PASSED BACK AT LEAST PARTLY TO SAID COMPRESSOR THROUGH SAID FIRST AND SECOND HEAT EXCHANGERS AND SAID INLET VALVE WHEREBY SAID EXPANDED AND COMPRESSED MEDIUM ARE IN THERMAL CONTACT, SAID FIRST HEAT EXCHANGER BEING AT LEAST IN PART A REGENERATOR, SAID REGENERATOR PART BEING IN OPEN COMMUNICATION WITH THE COMPRESSION SPACE OF SAID COMPRESSOR, SAID OUTLET AND INLET VALVES BEING IN COMMUNICATION WITH SAID FIRST HEAT EXCHANGER BEING LOCATED AT THE SIDE OF SAID REGENERATOR REMOTE FROM SAID COMPRESSION SPACE. 